Identification of two novel Mycobacterium avium allelic variants in pig and human isolates from Brazil by PCR-restriction enzyme analysis

Mycobacterium avium complex (MAC) is composed of environmental mycobacteria found widely in soil, water, and aerosols that can cause disease in animal s and humans, especially disseminated infections in AIDS patients. MAC cons ists of two closely related species, M. avium and M. intracellulare, and ma y also include other, less defined groups. The precise differentiation of M AC species is a fundamental step in epidemiological studies and for the eva luation of possible reservoirs for MAC infection in humans and animals, In this study, which included 111 pig and 26 clinical MAC isolates, two novel allelic M. avium PCR-restriction enzyme analysis (PRA) variants were identi fied, differing from the M. avium PRA prototype in the HaeIII digestion pat tern. Mutations in HaeIII sites were confirmed by DNA sequencing, Identific ation of these isolates as M, avium was confirmed by PCR with DT1-DT6 and I S1245 primers, nucleic acid hybridization,vith the Accu-Probe system, 16S r ibosomal DNA sequencing, and biochemical tests. The characterization of M. avium PRA variants can be useful in the elucidation of factors involved in mycobacterial virulence and routes of infection and also has diagnostic sig nificance, since they can be misidentified as M. simiae II and M. kansasii I if the PRA method is used in the clinical laboratory for identification o f mycobacteria.